Phospholipid fatty acid composition of various mouse tissues after feeding α‐linolenate (18∶3n−3) or eicosatrienoate (20∶3n−3)

The selective incorporation of dietary α‐linolenate (18∶3n−3) and its elongation product, eicosatrienoate (20∶3n−3), into various phospholipids (PL) of mouse liver, spleen, kidney, and heart, was examined in a two‐week feeding trial by assessing mol % changes in associated fatty acids. Mice were fed fat‐free AIN 76A diets modified with either 2 wt% safflower oil (control); 1% safflower and 1% linolenate; or 1% safflower and 1% eicosatrienoate. After linolenate or eicosatrienoate feeding, 20∶4n−6 was reduced by 36–50% in liver phosphatidylcholine (PC) and in liver and spleen phosphatidylethanolamine (PE). Linolenate was minimally incorporated into PL, but was desaturated and elongated to 20∶5n−3, 22∶5n−3, and 22∶6n−3, with notable differences in the quantity of these n−3 derivatives associated with different tissues and PL. Eicosatrientoate was uniquely incorporated into the cardiolipin (CL) pool of all organs. There was also considerable retroconversion of 20∶3n−3 to 18∶3n−3 (PC, PE). Dietary eicosatrienoate may therefore affect metabolism in diverse ways—20∶3n−3, which is retroconverted to 18∶3n−3, may provide substrate for 20∶5n−3 and 22∶6n−3 syntheses, whereas intact 20∶3n−3 may be incorporated into the CL pool. Acyl modifications of CL are known to affect the activity of key innermitochondrial enzymes, such as cytochrome c oxidase.